Then all you have to do is get the new replacement circuit board and replace it, there's a ribbon that connects the circle pad to the n3DS's motherboard, just carefully remove that and attach the new one.
Then just pop the new circle pad onto where the old one was, reassemble it and you're good to go.

Then all you have to do is get the new replacement circuit board and replace it, there's a ribbon that connects the circle pad to the n3DS's motherboard, just carefully remove that and attach the new one.
Then just pop the new circle pad onto where the old one was, reassemble it and you're good to go.